UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D C 20460
July 19, 1988
TWC A OJV I N I €. Y & A 7 Q W
SAB-SHC-88-033
Honorable Lee. M Thomas
Administrator
U. S» Environmental Protection Agency
401 M Street, s.W.
Washington, D.C. 20460
Subject: Science Advisory Board's review of the ETHYLBENZENE
health criteria document
Dear Mr. Thomas:
The Drinking Water Subcommittee of the Science Advisory
Board's Environmental Health Committee has completed its review
of the Drinking Water Health Criteria Document for Ethylbenzene
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We appreciate the opportunity to conduct this particular
scientific review. We request that the Agency formally respond
to the scientific advice provided, here.
Sincerely,
Norton Nelson, Chairman
Executive Committee
Richard A. Griesemer, Chairman
Environmental Health Committee
sd^fiS^L
Gary'p, Carlson, Chairman
Drinking Water Subcommittee
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SUBJECT: SCIENCE ADVISORY BOARD'S REVIEW OF THE ETHYLBENZEtJE
HEALTH CRITERIA DOCUMENT
SCIENCE ADVISORY BOARD COMMITTEE: DRINKING WATER SUBCOMMITTEE OF
THE ENVIRONMENTAL HEALTH COMMITTEE
DATE OF REVIEW? FEBRUARY 4-5, 1988
PLACE OF REVIEW: WASHINGTON CIRCLE HOTEL, WASHINGTON, D,C.
The Criteria Document for Ethylbenzene ("EB") is a clear
improvement over the previously reviewed Health Advisory ("HA").
Previous suggestions have been incorporated. The overall
inclusion of currently available and updated information
regarding uses, metabolism, level of exposure, general toxicology
and environmental impact helps to support the assessment of the
HA's Drinking Water Equivalent Level ("DWEL") and carcinogenicity
weight of evidence developed in the document. EB is a fugitive
compound in petroleum gasoline and gasoline products and is a
contaminant in ambient air (including tobacco smoke). Industrial
exposure occurs in production of petroleum products and
especially in the production of styrene for which it is a
chemical intermediate. It is considered a sentinel compound for
xylene, which can have as high as 20% EB in technical grade.
This relationship between ethylbenzene and xylene is generally
well stated throughout the document.
The basic issue concerning the calculation of the DWEL is
whether the subchronic study of Wolf et al (1956) using rats
given four dose levels of EB orally in olive oil over a six month
period should be used. The only other available data were from
abstracts of incompletely reported studies of questionable
reliability. The Wolf et al study has some uncertainties, such
as the usefulness of data derived from bolus administration in
olive oil, and incomplete toxicologieal profiling in that only
liver, blood and kidneys were examined. The study did establish
a dose response effect and a no observed effect level (NOEL) of .
136 mg/kg/day, subsequent evidence has indicated the relatively
rapid metabolism of ethylbenzene in humans to nontoxic
intermediates or metabolites. The chemical does not
bioaccumulate, is not in itself embryo or fetotoxic, is not
mutagenic and does not cause chromosomal damage where tested. On
the basis of these data the Subcommittee concurs that the Wolf et
al study should be used in calculating a DWEL for EB,
As with similar compounds, such as xylene, the DWEL is
greater than the odor or taste threshold. (DWEL is 3,4 mg/ml,
odor threshold is 0.2 mg/L and taste threshold is 0.1 mg/L) The
USEPA has set the ambient water quality level at 1.4 mg/L. We
recommend that the USEPA consider establishing a .secondary
standard for EB based on odor and taste. The 10 day Health
Advisory has been derived by dividing the 1 day HA by 10
and not on the basis of any direct data. The one day HA is based
on the somewhat soft data from the eight hour inhalation study of
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Bardodej and Ba,rdodejova (1970). The toxicokinetics are
suggestive, but not proof, that metabolism may have a limiting
effect on toxicity.
It is recognized that there are limited experimental data to
establish the toxicity of EB. This does not negate the
possibility of its having harmful effects when it is involved
with interactions with other chemicals, such as EB's potentiating
acrylonitrile mortality in rats and increasing teratogenic
effects in a xylene mixture, The Subcommittee recommends future
research regarding ethylbenzene's teratogenic potential and its
interaction in mixtures.
The Subcommittee agrees with the rating of D, not classified
as a human carcinogen, because of the lack of data. The
Subcommittee notes that the NIEHS started a 90 day bioassay study
using ethylbenaene on April 1, 1988. It will be followed by a
two year chronic study.
The exposure section does examine all potential routes of
exposure. Table IV-1, however, is misleading and should be
revised. The average ambient air and personal air concentrations
are significantly lower than the high exposure levels. If the
table included average exposure levels for rural/remote,
urban/suburban, and source-dominated areas, a more representative
description of exposure would be presented. Additional data are
available on EB's occurrence in drinking water and food which
should be included in this section—see the following papers;
otsen, R., D.T. Williams and P.O. Bothwell (1982) volatile
Organic Compounds in Water at Thirty Canadian Potable Water
Treatment Facilities, J. Assoc* Off. Anal. Chem., 65:1370-1374
and Min, D.B.S., K» Ina, R. J. Peterson and s.s. Chang (1979),
Preliminary Identification of Volatile Flavor Compounds in the
Neutral Fraction of Waste Beef, J. Food. Sei,, 44J639-642.
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U.S. Environmental Protection Agency
Science Advisory Board
Drinking Water Subcommittee
CHAIRMAN, AMP VICE CHAIRMAN
Dr. Gary Carlson [CHAIR], Department of pharmacology and Toxicology, School
of Pharmacy, Purdue University, West Lafayette, Indiana 4790?
Dr. Robert Tardiff, [VICE-CHAIR], Principal, Environ Corporation, 1QOO Potomac
St., N.W., Terrace Level, Washington, DC 20007
MEMBERS AND CONSULTANTS
Dr. Julian B. Andelman, Graduate School of Public Health» 130 Desoto Street,
Parran Hall - Room A-711, University of Pittsburgh, Pittsburgh, PA 15261
Dr. Rose Dagirmanjtan, Professor, Department of Pharmacology and Toxicology,
University of Louisville, Louisville, Kentucky 40292
Dr. William Glaze, Director, School of Public Health, University of California,
Los Angeles, 650 Circle, Drive South, Los Angeles, CA 90024
Dr. J. Donald Johnson, Professor, School of Public Health, University of
North Carolina, Chapel Hill, NC 27514
Dr. David Kaufman, Department of Pathology, University of North Carolina,
Rfli. 515 Brinkhous-Bullitt, Chapel Hill, North Carolina 27514
Dr. Nancy Kim, Director, New York Department of Health, Bureau of Toxic
Substance Assessment, Room 359, Tower Building, Empire State Plaza, Albany,
New York 12037
Dr. Verne Ray, Medical Research Laboratory, Pfizer, Inc. Groton, Connecticut,
06340
Dr. Harold Sehechter, Professor, Chemistry Department, Ohio State University,
140 West 18th Avenue, Columbus, Ohio 43201
Or. Thomas Tephly, Professor, Department of Pharmacology, The Bowen
Science Bldg., University of Iowa, Iowa City, Iowa 52242
EXECUTIVE SECRETARY
Dr. C. Richard Cothern, Executive Secretary, Science Advisory Board
[A-101F] U.S. Environmental Protection Agency, Washington, D.C. 20460
(202) 382-2552
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